- BlackBerry Enterprise Server for Microsoft Exchange 5.0 SP1 to SP4
When deploying a new BlackBerry Enterprise Server in a Microsoft Exchange 2010 environment, or when migrating an existing environment to Exchange 2010, there are several considerations that should be made with regard to BlackBerry Service Account used.
The main points to consider with regard to the BlackBerry Service Account are:
- The version of the Microsoft Exchange server where the BlackBerry service account is hosted
- The physical location of the BlackBerry service account mailbox
- The number of BlackBerry service accounts used
- The home Client Access Server (CAS) or CAS Array(s) of the BlackBerry service account
- The distribution of user mailboxes and the version of Microsoft Exchange that their mailboxes reside on
Most of these considerations do not apply to environments where all BlackBerry users are hosted on Exchange 2003 and/or Exchange 2007 mailbox servers. These considerations can become extremely important with mixed environments (coexistance between Exchange 2003/2007 and Exchange 2010), and also brand new stand-alone Exchange 2010 environments.
Version of Microsoft Exchange server where the BlackBerry Service Account is hosted
The BlackBerry Service Account mailbox must reside on an Exchange 2010 mailbox server if the BlackBerry Enterprise Server services any users whose mailboxes reside on an Exchange 2010 mailbox server. While the BlackBerry Enterprise Server may appear to function if the BlackBerry Service Account is still hosted on Exchange 2003/2007, this configuration is not supported and will likely cause problems.
Prior to adding or migrating any BlackBerry enabled users to Exchange 2010, the BlackBerry Service Account mailbox must first be migrated to Exchange 2010, or a new service account must be created and the BlackBerry Enterprise Server must be switched to use the new BlackBerry Service Account. Please see KB04293 for steps on how to switch the service account.
Physical location of the BlackBerry Service Account mailbox
Due to how MAPI traffic functions in an Exchange 2010 environment, the physical location of the BlackBerry Service Account in relationship to the location of the BlackBerry Enterprise Server and the users' mailboxes can have a significant impact.
The service account mailbox should be located as close to the BlackBerry Enterprise Server as possible, which in turn should be located as close to the users' mailboxes as possible. If the service account mailbox resides remotely, CAS proxying may take place (see below), which can have a negative impact on RPC latency and performance and could cause mail delays.
If there are multiple Exchange sites (with associated CAS arrays at each site), each BlackBerry Enterprise Server, or group of servers, at a given site should use a separate BlackBerry Service Account.
Number of BlackBerry Service Acounts used
Whether to use a single BlackBerry Service Account for each BlackBerry Enterprise server or a shared service account for a group of BlackBerry Enterprise Servers depends on several factors, and there is no hard and fast rule. There are advantages and disadvantages to using more/fewer accounts, but at minimum it is best to use a single service account per site/CAS array.
Advantages to using a single account for each BlackBerry Enterprise Server include:
- More fault tolerant because each account can have a mailbox hosted on a different Exchange server. If an Exchange server goes down, only one BlackBerry Enterprise Server would be impacted
- Less impact from unintentional throttling issues, such as problems with falling back to the default throttling policy (see KB20608) or NSPI connection limits (see KB17325)
- May be easier to profile and troubleshoot the load that each individual BlackBerry Enterprise Server is putting on Exchange
Advantages to using a single service account for a group of BlackBerry Enterprise Servers in a site:
- Easier to manage, especially if corporate policy dictates frequent password changes
- Less likely to encounter problems due to inconsistent configuration of multiple accounts
Location of the home Client Access Server of the BlackBerry Service Account
In Exchange 2010, each mailbox enabled account has a home CAS which determines the RPC Endpoint for all RPC connections. Since the BlackBerry Enterprise Server connects via MAPI and MAPI is based on RPC, this can have significant impact on the performance of the BlackBerry Enterprise Server. The home CAS can be determined by the RPCClientAccessServer property on the mailbox database.
If the BlackBerry Service Account's RPCClientAccessServer is not the same as that of the BlackBerry smartphone users being hosted on the BlackBerry Enterprise Server, connections to users' mailboxes may be required to proxy through one CAS before going to the destination CAS. This likely wouldn't be noticeable in a LAN or low-latency WAN, but in a high-latency WAN it could cause significant impact.
For example, if the BlackBerry Enterprise Server is in EMEA along with all the BlackBerry smartphone users' mailboxes (which all have an RPCClientAccessServer value of emea.company.com), and the BlackBerry Service Account's mailbox is in NA, with an RPCClientAccessServer value of na.company.com, then connections to users' mailboxes may need to be proxied through North America, even though the server and mailboxes are both in EMEA.
Distribution of user mailboxes and the version of Microsoft Exchange that their mailboxes reside on
In general, it is acceptable to have a mix of Exchange 2010 and Exchange 2003/2007 users coexisting on the same BlackBerry Enterprise Server, so long as the appropriate permissions and minimum requirements are met for both versions of Exchange.
However, there are some considerations to be made based on the user distribution:
- In a mixed environment where the BlackBerry Service Account resides on Exchange 2010, Exchange 2003 or 2007 servers may report that the service account has reached the maximum allowable session limit. See KB20066 for more information about this issue.
- Depending on the number of BlackBerry smartphone users on the BlackBerry Enterprise Server and the number of users on each version of Exchange, user distribution across agents may not appear balanced. For example, there may be 400 Exchange 2010 users all on the same agent, and then the remaining agents may only have 50 users each from different Exchange 2003/2007 servers. This is normal, as the BlackBerry Enterprise Server automatically groups users by like Exchange server. In the case of Exchange 2010 users, the CAS URL will be the same for all users, and they will be grouped together.
Once users have been fully migrated to Exchange 2010 and there are no more BlackBerry users on the server whose mailboxes reside on Exchange 2003/2007, it is advisable to modify the user distribution algorithm used by the BlackBerry Dispatcher service to balance users across agents. Since all users will appear to be on the same Exchange server, we can modify the algorithm to use simple optimization to balance users equally across all agents instead of loading up each agent fully with like Exchange servers and then adding agents as needed. This can often result in improved performance. Note, however, that this change should not be made until all users on the BlackBerry Enterprise Server reside on Exchange 2010 mailbox servers.
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